Photonic crystals are periodic arrangements of dielectric elements having strong index contrast. Two-dimensional photonic crystals can be constituted by arrays of parallel columns of dielectric material or arrays of parallel cylindrical holes formed in a dielectric substrate. Waveguides can be formed in such components by missing rows of columns or holes.
It is known, in particular from the article “Mini-stopbands of one-dimensional system: the channel waveguide in a two-dimensional photonic crystal ” by S. Olivier, M. Rattier, H. Benisty, C. Weisbuch et al., Physical Review B, Vol. 63, 113311 of Mar. 1, 2001, that a waveguide in a photonic crystal presents photonic band gaps or mini-stopbands (MSB) because of coupling between the fundamental mode and the higher order modes in the waveguide, the frequencies of these non-transmission bands being determined in particular by dimensional parameters of the photonic crystal (period, dimension, and shape of the elements, fill factor, . . . ), and by the width of the waveguide.